Delivery of pharmaceutical agents via the human insulin receptor

ABSTRACT

A humanized murine antibody is provided that binds to the human insulin receptor (HIR). The humanized murine antibody is suitable for use as a Trojan horse to deliver pharmaceutical agents to human organs and tissue that express the HIR. The humanized murine antibody is especially well suited for delivering neuropharmaceutical agents from the blood stream to the brain across the blood brain barrier (BBB). The humanized murine antibody may be genetically fused to the pharmaceutical agent or it may be linked to the pharmaceutical agent using an avidin-biotin conjugation system.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.10/307,276, filed Nov. 27, 2002 now U.S. Pat. No. 7,388,079, thespecification of which is incorporated herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to the delivery ofpharmaceutical agents from the blood stream to the human brain and otherorgans or tissues that express the human insulin receptor. Moreparticularly, the present invention involves the development of“humanized” monoclonal antibodies (MAb) that may be attached topharmaceutical agents to form compounds that are able to readily bind tothe human insulin receptor (HIR). The compounds are able to cross thehuman blood brain barrier (BBB) by way of insulin receptors located onthe brain capillary endothelium. Once across the BBB, the humanizedmonoclonal antibody/pharmaceutical agent compounds are also capable ofundergoing receptor mediated endocytosis into brain cells via insulinreceptors located on the brain cells.

2. Description of Related Art

The publications and other reference materials referred to herein todescribe the background of the invention and to provide additionaldetail regarding its practice are hereby incorporated by reference. Forconvenience, the reference materials are identified by author and dateand grouped in the appended bibliography.

The BBB is a system-wide membrane barrier that prevents the brain uptakeof circulating drugs, protein therapeutics, antisense drugs, and genemedicines. Drugs or genes can be delivered to the human brain for thetreatment of serious brain disease either (a) by injecting the drug orgene directly into the brain, thus bypassing the BBB, or (b) byinjecting the drug or gene into the bloodstream so that the drug or geneenters the brain via the transvascular route across the BBB. Withintra-cerebral administration of the drug, it is necessary to drill ahole in the head and perform a procedure called craniotomy. In additionto being expensive and highly invasive, this craniotomy based drugdelivery to the brain approach is ineffective, because the drug or geneis only delivered to a tiny volume of the brain at the tip of theinjection needle. The only way the drug or gene can be distributedwidely in the brain is the transvascular route following injection intothe bloodstream. However, this latter approach requires the ability toundergo transport across the BBB. The BBB has proven to be a verydifficult and stubborn barrier to traverse safely.

Prior work has shown that drugs or gene medicines can be ferried acrossthe BBB using molecular Trojan horses that bind to BBBreceptor/transport systems. These Trojan horses may be modifiedproteins, endogenous peptides, or peptidomimetic monoclonal antibodies(MAb's). For example, HIR MAb 83-14 is a murine MAb that binds to thehuman insulin receptor (HIR). This binding triggers transport across theBBB of MAb 83-14 (Pardridge et al, 1995), and any drug or gene payloadattached to the MAb (Wu et al., 1997).

The use of molecular Trojan horses to ferry drugs or genes across theBBB is described in U.S. Pat. Nos. 4,801,575 and 6,372,250. The linkingof drugs to MAb transport vectors is facilitated with use ofavidin-biotin technology. In this approach, the drug or proteintherapeutic is monobiotinylated and bound to a conjugate of the antibodyvector and avidin or streptavidin. The use of avidin-biotin technologyto facilitate linking of drugs to antibody-based transport vectors isdescribed in U.S. Pat. No. 6,287,792. Fusion proteins have also beenused where a drug is genetically fused to the MAb transport vector.

HIRMAb 83-14 has been shown to rapidly undergo transport across the BBBof a living Rhesus monkey, and to bind avidly to isolated human braincapillaries, which are the anatomical substrate of the human BBB (seePardridge et al., 1995). In either case, the activity of the HIRMAb83-14 with respect to binding and transport at the primate or human BBBis more than 10-fold greater than the binding or transport of otherpeptidomimetic MAb's that may target other BBB receptors such as thetransferrin receptor (Pardridge, 1997). To date, HIRMAb 83-14 is themost active BBB transport vector known (Pardridge, 1997). On this basis,the HIRMAb 83-14 has proven to be a very useful agent for the deliveryof drugs to the primate brain in vivo, and would also be highly activefor brain drug or gene delivery to the brain in humans.

HIRMAb 83-14 cannot be used in humans because this mouse protein will beimmunogenic. Genetically engineered forms of HIRMAb 83-14 might be usedin humans in either the form of a chimeric antibody or a geneticallyengineered “humanized” HIRMAb. However, in order to perform the geneticengineering and production of either a chimeric or a humanized antibody,it is necessary to first clone the variable region of the antibody heavychain (VH) and the variable region of the antibody light chain (VL).Following cloning of the VH and VL genes, the genes must be sequencedand the amino acid sequence deduced from the nucleotide sequence. Withthis amino acid sequence, using technologies known to those skilled inthe art (Foote et al., 1992), it may be possible to perform humanizationof the murine HIRMAb 83-14. However, HIRMAb 83-14 may lose biologicalactivity following the humanization (Pichla et al., 1997). Therefore, itis uncertain as to whether the murine HIRMAb can be humanized withretention of biological activity.

A chimeric form of the HIRMAb 83-14 has been genetically engineered, andthe chimeric antibody binds to the HIR and is transported into theprimate brain (Coloma et al., 2000). However, a chimeric antibodyretains the entire mouse FR for both the VH and the VL, and because ofthis, chimeric antibodies are still immunogenic in humans (Bruggemann etal., 1989). In contrast to the chimeric antibody, a humanized antibodywould use the human FR amino acid sequences for both the VH and the VLand retain only the murine amino acids for the 3 complementaritydetermining regions (CDR's) of the VH and 3 CDR's of the VL. Not allmurine MAb's can be humanized, because there is a loss of biologicalactivity when the murine FR's are replaced by human FR sequences (Pichlaet al., 1997). The biological activity of the antibody can be restoredby substituting back certain mouse FR amino acids (see U.S. Pat. No.5,585,089). Nevertheless, even with FR amino acid back-substitution,certain antibodies cannot be humanized with retention of biologicalactivity (Pichla et al., 1997). Therefore, there is no certainty thatthe murine HIRMAb 83-14 can be humanized even once the key murine CDRand FR amino acid sequences are known.

SUMMARY OF THE INVENTION

In accordance with the present invention, it was discovered that themurine HIRMAb 83-14 antibody can be humanized to provide a biologicallyactive humanized insulin receptor (HIR) antibody that may be used incombination with drugs and diagnostic agents to treat human beings invivo. The HIR antibody may be conjugated to the drug or diagnostic agentusing avidin-biotin conjugation or the HIR antibody/drug combination maybe prepared as a fusion protein using genetic engineering techniques.The HIR antibody is especially well suited for deliveringneuropharmaceutical agents to the human brain across the BBB. Thehumanized character of the HIR antibody significantly reducesimmunogenic reactions in humans.

The humanized murine antibody of the present invention is capable ofbinding to the HIR and includes a heavy chain (HC) of amino acids and alight chain (LC) of amino acids which both include variable and constantregions. The variable regions of the HC and LC include complementaritydetermining regions (CDRs) that are interspersed between frameworkregions (FRs).

The HC includes a first CDR located at the amino end of the variableregion, a third CDR located at the carboxyl end of the HC variableregion and a second CDR located between said first and third CDRs. Theamino acid sequence for the first CDR is SEQ. ID. NO. 31 and equivalentsthereof, the amino acid sequence for the second CDR is SEQ. ID. NO. 33and equivalents thereof and the amino acid sequence for the third CDR isSEQ. ID. NO. 35 and equivalents thereof. The HC framework regionsinclude a first FR located adjacent to the amino end of the first CDR, asecond FR located between said first and second CDRs, a third FR locatedbetween said second and third CDRs and a fourth FR located adjacent tothe carboxyl end of said third CDR. In accordance with the presentinvention, the four FRs of the HC are humanized such that the overallantibody retains biological activity with respect to the HIR and is notimmunogenic in humans.

The LC also includes a first CDR located at the amino end of thevariable region, a third CDR located at the carboxyl end of the variableregion and a second CDR located between said first and third CDRs. Theamino acid sequence for the first CDR is SEQ. ID. NO. 38 and equivalentsthereof, the amino acid sequence for the second CDR is SEQ. ID. NO. 40and equivalents thereof and the amino acid sequence for the third CDR isSEQ. ID. NO. 42 and equivalents thereof. The LC framework regionsinclude a first FR located adjacent to the amino end of said first CDR,a second FR located between said first and second CDRs, a third FRlocated between said second and third CDRs and a fourth FR locatedadjacent to the carboxyl end of said third CDR. Pursuant to the presentinvention, the four FRs of the LC are humanized such that the overallantibody retains biological activity with respect to the HIR and hasminimal immunogenicity in humans.

The constant regions of the murine antibody are also modified tominimize immunogenicity in humans. The murine HC constant region isreplaced with the HC constant region from a human immunoglobulin such asIgG1. The murine LC constant region is replaced with a constant regionfrom the LC of a human immunoglobulin such as a κ LC constant region.Replacement of the murine HC and LC constant regions with human constantregions was found to not adversely affect the biological activity of thehumanized antibody with respect to HIR binding.

The present invention not only covers the humanized murine antibodiesthemselves, but also covers pharmaceutical compositions that arecomposed of the humanized antibody linked to a drug or diagnostic agent.The humanized antibody is effective in delivering the drug or diagnosticagent to the HIR in vivo to provide transport across the BBB and/orendocytosis into cells via the HIR. The compositions are especially wellsuited for intra venous (iv.) injection into humans for delivery ofneuropharmaceutical agents to the brain.

The above discussed and many other features and attendant advantages ofthe present invention will become better understood by reference to thedetailed description when taken in conjunction with the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the nucleotide sequence for the murine VH (SEQ. ID. NO. 1)and murine VL (SEQ. ID. NO. 2) and deduced amino acid sequence of themurine VH (SEQ. ID. NO. 3) and the murine VL (SEQ. ID. NO. 4), whichshows the 3 framework (FR) regions and the 4 complementarity determiningregions (CDRs) of both the heavy chain (HC) and the light chain (LC) ofthe 83-14 murine HIRMAb. The amino acids denoted by an asterisk (*) wereconfirmed by amino acid sequencing of either the intact murine LC ortryptic peptides of the intact murine HC; for amino acid sequencing, theintact murine HC or LC were purified from gels following purification ofthe intact murine IgG from the hybridoma conditioned medium.

FIGS. 2A and 2B graphically show the results of a radio-receptor assayon isolated human brain capillaries that were obtained with a mechanicalhomogenization procedure from human autopsy brain. These capillarieswere incubated with [¹²⁵I]-labeled chimeric HIRMAb (Coloma et al., 2000)(FIG. 2A) or [¹²⁵I]-version 5 humanized HIRMAb (FIG. 2B). The data showthat both antibodies bind equally well to human brain capillaries, whichform the anatomical basis of the BBB in humans.

FIG. 3 shows the brain scan of a Rhesus monkey treated with a humanizedmonoclonal antibody in accordance with the present invention. The[¹²⁵I]-labeled version 5 HIRMAb was injected intravenously in ananesthetized rhesus monkey, and the animal was euthanized 120 minuteslater. The brain was rapidly removed and cut into coronal hemisphericslabs, which were immediately frozen. Cryostat sections (20 μm) were cutand exposed to x-ray film. The film was scanned to yield the image shownin FIG. 3. This image shows the clear demarcations between the graymatter and white matter of the primate brain. Owing to the highervascular density in gray matter, there is a greater uptake of thehumanized HIRMAb, relative to white matter.

FIG. 4 shows a comparison of the amino acid sequence for the 3 FRs and 3CDRs of both the heavy chain and the light chain for the following: (a)the version 5 humanized HIRMAb, (v) the original murine 83-14 HIRMAb,and (c) the VH of the B43 human IgG or the VL of the REI human IgG.

FIG. 5 shows the amino acid sequence of a fusion protein of humanα-L-iduronidase (IDUA) (SEQ. ID. NO. 48), which is fused to the carboxylterminus of the heavy chain (HC) of the humanized monoclonal antibody tothe human insulin receptor (HIRMAb). The HC is comprised of a variableregion (VH) and a constant region (CH); the CH is further comprised of 3sub-regions, CH1 (SEQ. ID. NO. 44), CH2 (SEQ. ID. NO. 45), and CH3 (SEQ.ID NO. 46); the CH1 and CH2 regions are connected by a 12 amino acidhinge region (SEQ. ID. NO. 47). The VH is comprised of 4 frameworkregions (FR1=SEQ. ID. NO. 30; FR2=SEQ. ID. NO. 32; FR3=SEQ. ID. NO. 34;and FR4=SEQ. ID. NO. 36) and 3 complementarity determining regions (CDR)(CDR1=SEQ. ID. NO. 31; CDR2=SEQ. ID. NO. 33; and CDR3=SEQ. ID. NO. 35).The amino acid sequence shown for the CH is well known in existingdatabases and corresponds to the CH sequence of human IgG1. There is asingle N-linked glycosylation site on the asparagine (N) residue withinthe CH2 region of the CH, and there are 6 potential N-linkedglycosylation sites within the IDUA sequence, as indicated by theunderline.

DETAILED DESCRIPTION OF THE INVENTION

The present invention involves the humanization of the murine monoclonalantibody identified as MAb 83-14 so that it can be used in vivo inhumans. As previously mentioned, MAb 83-14 has a high affinity for thehuman insulin receptor at the human or rhesus monkey blood-brain barrier(Pardridge, et al. 1995) and is a candidate for use as a Trojan horse totransport neuropharmaceutical agents across the BBB. As used herein, theterm “pharmaceutical agents” is intended to include any drug, gene orchemical that is used to treat or diagnose disease in humans. The term“neuropharmaceutical agent” covers pharmaceutical agents that are usedto treat brain disease. The present humanized antibody Trojan horses areespecially well-suited for transporting neuropharmaceutical agents fromthe blood stream to the brain across the BBB.

The complete amino acid sequence for the variable region of the HC andLC of murine Mab 83-14 was determined as described in Example 1. Thenucleotide sequence for the gene that expresses the murine VH (SEQ. ID.NO. 1) and the murine VL (SEQ. ID. NO. 2) is set forth in FIG. 1. Theamino acid sequence for the murine VH (SEQ. ID. NO. 3) and murine VL(SEQ. ID. NO. 4) is also set forth in FIG. 1. The amino acid sequencesfor the variable regions of the murine MAb 83-14 VH and VL are also setforth in FIG. 4 (SEQ. ID. NOS. 3 AND 4, respectively). The humanizedmurine antibodies of the present invention are prepared by modifying theamino acid sequences of the variable regions of the murine antibody tomore closely resemble human antibody without destroying the ability ofthe antibody to strongly bind to the HIR. In addition, the humanizedantibody includes constant regions that also correspond to humanantibody.

The humanized murine antibodies include a heavy chain of amino acids(HC) that is composed of a constant region (CH) and a variable region(VH). The variable region of the HC has an amino end and a carboxyl endand includes three CDRs interspersed between four FRs. The first CDR(CDR1) is located towards the amino end of the VH with the third CDR(CDR3) being located towards the carboxyl end of the HC. The amino acidsequences for murine MAb 83-14 HC CDR1, CDR2, and CDR3 are set forth inSEQ. ID. NOS. 31, 33 and 35, respectively. Since the HC CDRs areessential for antibody binding to the HIR, it is preferred that thehumanized antibodies have HC CDRs with amino acid sequences that areidentical to SEQ. ID. NOS. 31, 33 and 35. However, the humanizedantibodies may include CDRs in the HC that have amino acid sequenceswhich are “individually equivalent” to SEQ. ID. NOS. 31, 33 and 35.“Individually Equivalent” amino acid sequences are those that have atleast 75 percent sequence identity and which do not adversely affect thebinding of the antibody to the HIR. Preferably, individually equivalentamino acid sequences will have at least 85 percent sequence identitywith SEQ. ID. NOS. 31, 33 or 35. Even more preferred are individuallyequivalent amino acid sequences having at least 95 percent sequenceidentity.

The three VH CDR amino acid sequences may also be viewed as a combinedgroup of amino acid sequences (VH CDR1, VH CDR2 and VH CDR3). Thepresent invention also covers equivalents of the combined group of VHCDR sequences. Such “combined equivalents” are those that have at least75 percent sequence identity with the combined amino acid sequences SEQ.ID. NOS. 31, 32 and 35 and which do not adversely affect the binding ofthe antibody to the HIR. Preferably, combined equivalent amino acidsequences will have at least 85 percent sequence identity with thecombined sequences found in SEQ. ID. NOS. 31, 33 and 35. Even morepreferred are combined equivalent amino acid sequences that have atleast 95 percent sequence identity with the combined amino acidsequences (SEQ. ID. NOS. 31, 33 and 35).

It is preferred that the VH CDR amino acid sequences meet both theindividual equivalency and combined equivalency requirements set forthabove. However, there are certain situations, especially for the shorterCDR's, where one or more of the CDR's may not meet the criteria forindividual equivalence eventhough the criteria for combined equivalenceis met. In such situations, the individual equivalency requirements arewaived provided that the combined equivalency requirements are met Forexample, VH CDR3 (SEQ. ID. NO. 35) is only 4 amino acids long. If twoamino acids are changed, then the individual sequence identity is only50% which is below the 75% floor for individual equivalence set forthabove. However, this particular sequence is still suitable for use aspart of a combined equivalent VH CDR group provided that the sequenceidentity of the combined CDR1, CDR2 and CDR3 sequences meet the groupequivalency requirements.

The humanized murine antibodies also include a light chain (LC) of aminoacids that is composed of a constant region (CL) and a variable region(VL). The variable region of the LC has an amino end and a carboxyl endand includes three CDRs interspersed between four FRs. The first CDR(CDR1) is located towards the amino end of the VL with the third CDR(CDR3) being located towards the carboxyl end of the VL. The amino acidsequences for murine MAb 83-14 LC CDR1, CDR2, and CDR3 are set forth inSEQ. ID. NOS. 38, 40 and 42, respectively. Since the VL CDRs are alsoimportant for antibody binding to the HIR, it is preferred that thehumanized antibodies have LC CDRs with amino acid sequences that areidentical to SEQ. ID. NOS. 38, 40 and 42. However, the humanizedantibodies may include CDRs in the VL that have amino acid sequenceswhich are “individually equivalent” to SEQ. ID. NOS. 38, 40 or 42.“Individually equivalent” amino acid sequences are those that have atleast 75 percent sequence identity and which do not adversely affect thebinding of the antibody to the HIR. Preferably, individually equivalentamino acid sequences will have at least 85 percent sequence identitywith SEQ. ID. NOS. 38, 40 or 42. Even more preferred are individuallyequivalent amino acid sequences having at least 95 percent sequenceidentity.

The three VL CDR amino acid sequences may also be viewed as a combinedgroup of amino acid sequences (VL CDR1, VL CDR2 and VL CDR3). Thepresent invention also covers equivalents of the combined group of VLCDR sequences. Such “combined equivalents” are those that have at least75 percent sequence identity with the combined amino acid sequences SEQ.ID. NOS. 38, 40 and 42 and which do not adversely affect the binding ofthe antibody to the HIR. Preferably, combined equivalent amino acidsequences will have at least 85 percent sequence identity with thecombined sequences found in SEQ. ID. NOS. 38, 40 and 42. Even morepreferred are combined equivalent amino acid sequences that have atleast 95 percent sequence identity with the combined amino acidsequences (SEQ. ID. NOS. 38, 40 and 42).

It is preferred that the VL CDR amino acid sequences meet both theindividual equivalency and combined equivalency requirements set forthabove. However, there are certain situations, especially for the shorterCDR's, where one or more of the CDR's may not meet the criteria forindividual equivalence eventhough the criteria for combined equivalenceis met. In such situations, the individual equivalency requirements arewaived provided that the combined equivalency requirements are met. Forexample, VH CDR3 (SEQ. ID. NO. 42) is only 9 amino acids long. If threeamino acids are changed, then the individual sequence identity is only66% which is below the 75% floor for individual equivalence set forthabove. However, this particular sequence is still suitable for use aspart of a combined equivalent VL CDR group provided that the sequenceidentity of the combined CDR1, CDR2 and CDR3 sequences meet the groupequivalency requirements.

The first framework region (FR1) of the VH is located at the amino endof the humanized antibody. The fourth framework region (FR4) is locatedtowards the carboxyl end of the humanized antibody. Exemplary preferredamino acid sequences for the humanized VH FR1, FR2, FR3 and FR4 are setforth in SEQ. ID. NOS. 30, 32, 34 and 36, respectively, and thesepreferred sequences correspond to version 5 humanized HIRMAb (Table 3).The amino acid sequence for FR2 (SEQ. ID. NO. 32) is identical to theamino acid sequence of murine MAb 83-14 VH FR2 or the human IgG, B43(See FIG. 4). The amino acid sequences for VH FR1 and FR4 (SEQ. ID. NOS.30 and 36) correspond to the B43 human antibody framework regions thathave amino acid sequences that differ from murine MAb 83-14 (FIG. 4).The amino acid sequences for the VH FR3 (SEQ. ID. No. 34) of the version5 humanized HIRMAb corresponds to the VH FR3 of the murine 83-14antibody (Table 3). It is possible to modify the preferred VH FRsequences without destroying the biological activity of the antibody.Suitable alternate or equivalent FRs include those that have at least 70percent individual sequence identity with SEQ. ID. NOS. 30, 32, 34 or 36and do not destroy the resulting antibodies ability to bind the HIR.Preferably, the alternate FRs will have at least 80 percent sequenceidentity with the preferred VH FR that is being replaced. Even morepreferred are alternate FRs that have at least 90 percent sequenceidentity with the preferred VH FR that is being replaced.

The four VH FR amino acid sequences may also be viewed as a combinedgroup of amino acid sequences (VH FR1, VH FR2, VH FR3 and VH FR4). Thepresent invention also covers alternates or equivalents of the combinedgroup of VH FR sequences. Such “combined equivalents” are those thathave at least 70 percent sequence identity with the combined amino acidsequences SEQ. ID. NOS. 30, 32, 34 and 36 and which do not adverselyaffect the binding of the antibody to the HIR. Preferably, combinedequivalent amino acid sequences will have at least 80 percent sequenceidentity with the combined sequences found in SEQ. ID. NOS. 30, 32, 34and 36. Even more preferred are combined equivalent amino acid sequencesthat have at least 90 percent sequence identity with the combined aminoacid sequences (SEQ. ID. NOS. 30, 32, 34 and 36).

It is preferred that the alternate VH FR amino acid sequences meet boththe individual equivalency and combined equivalency requirements setforth above. However, there are certain situations, especially for theshorter FR's, where one or more of the FR's may not meet the criteriafor individual equivalence even though the criteria for combinedequivalence is met. In such situations, the individual equivalencyrequirements are waived provided that the combined equivalencyrequirements are met.

The first framework region (FR1) of the LC is located at the amino endof the VL of the humanized antibody. The fourth framework region (FR4)is located towards the carboxyl end of the VL of the humanized antibody.Exemplary preferred amino acid sequences for the humanized VL FR1, FR2,FR3 and FR4 are set forth in SEQ. ID. NOS. 37, 39, 41 and 43,respectively. The amino acid sequences for LC FR1, FR2, FR3 and FR4(SEQ. ID. NOS. 37, 39, 41 and 43) correspond to the REI human antibodyframework regions that have amino acid sequences that differ from murineMAb 83-14 (See FIG. 4). It is possible to modify the preferred VL FRsequences without destroying the biological activity of the antibody.Suitable alternate or equivalent FRs include those that have at least 70percent sequence identity with SEQ. ID. NOS. 37, 39, 41 and 43 and donot destroy the resulting antibodies ability to bind the HIR.Preferably, the equivalent or alternate FRs will have at least 80percent sequence identity with the preferred VL FR that is beingreplaced. Even more preferred are alternate FRs that have at least 90percent sequence identity with the preferred VL FR that is beingreplaced.

The four VL FR amino acid sequences may also be viewed as a combinedgroup of amino acid sequences (VL FR1, VL FR2, VL FR3 and VL FR4). Thepresent invention also covers alternates or equivalents of the combinedgroup of VL FR sequences. Such “combined equivalents” are those thathave at least 70 percent sequence identity with the combined amino acidsequences SEQ. ID. NOS. 37, 39, 41 and 43 and which do not adverselyaffect the binding of the antibody to the HIR. Preferably, combinedequivalent amino acid sequences will have at least 80 percent sequenceidentity with the combined sequences found in SEQ. ID. NOS. 37, 39, 41and 43. Even more preferred are combined equivalent amino acid sequencesthat have at least 90 percent sequence identity with the combined aminoacid sequences (SEQ. ID. NOS. 37, 39, 41 and 43).

It is preferred that the alternate VL FR amino acid sequences meet boththe individual equivalency and combined equivalency requirements setforth above. However, there are certain situations, especially for theshorter FR's, where one or more of the FR's may not meet the criteriafor individual equivalence eventhough the criteria for combinedequivalence is met. In such situations, the individual equivalencyrequirements are waived provided that the combined equivalencyrequirements are met.

Version 5 is a preferred humanized antibody in accordance with thepresent invention. The amino acid sequences for the VH and VL of Version5 are set forth in SEQ. ID. NOS. 5 and 6, respectively. The preparationand identification of Version 5 is set forth in more detail in Example2, Table 3 and FIG. 4. The amino acid sequences for the VH FRs ofVersion 5 correspond to the preferred VH FR sequences set forth above(SEQ. ID. NOS. 30, 32, 34 and 36). In addition, the amino acid sequencesfor the VL FRs of Version 5 correspond to the preferred VL FR sequencesset forth above (SEQ. ID. NOS. 37, 39, 41, 43). The VH and VL FRs ofVersion 5 are a preferred example of VH and VL LC FRs that have been“humanized”. “Humanized” means that the four framework regions in eitherthe HC or LC have been matched as closely as possible with the FRs froma human antibody (HAb) without destroying the ability of the resultingantibody to bind the HIR. The model human antibody used for the HC isthe B43 antibody, and the model human antibody used for the LC is theREI antibody, and both the B43 and REI antibody sequences are well knownand available in public databases. When the HC or LC FRs are humanized,it is possible that one or more of the FRs will not correspondidentically with the chosen HAb template and may retain identity orsimilarity to the murine antibody. The degree to which murine amino acidsequences are left in the humanized FRs should be kept as low aspossible in order to reduce the possibility of an immunogenic reactionin humans.

Examples of FRs that have been humanized are set forth in Example 2 andTable 3. Framework regions from human antibodies that correspond closelyto the FRs of murine MAb 84-13 are chosen. The human FRs are thensubstituted into the MAb 84-13 in place of the murine FRs. The resultingantibody is then tested. The FRs, as a group, are only considered to behumanized if the modified antibody still binds strongly to the HIRreceptor and has reduced immunogenicity in humans. If the first test isnot successful, then the human FRs are modified slightly and theresulting antibody tested. Exemplary human antibodies that have HC FRsthat may be used to humanize the HC FRs of MAb 84-13 include B43 humanIgG (SEQ. ID. NO. 12), which is deposited in Genbank (accession numberS78322), and other human IgG molecules with a VH homologous to themurine 83-14 VH may be found by searching public databases, such as theKabat Database of immunoglobulin sequences. Exemplary human antibodiesthat have LC FRs that may be used to humanize the LC FRs of MAb 84-13include human REI antibody (SEQ. ID. NO. 13), which is deposited inGenbank (accession number 1WTLB), and other human IgG molecules with aVL homologous to the murine 83-14 VL may be found by searching publicdatabases, such as the Kabat Database of immunoglobulin sequences.

In order for the humanized antibody to function properly, the HC and LCshould each include a constant region. Any number of different humanantibody constant regions may be incorporated into the humanizedantibody provided that they do not destroy the ability of the antibodyto bind the HIR. Suitable human antibody HC constant regions includehuman IgG1, IgG2, IgG3, or IgG4. The preferred HC constant region ishuman IgG1. Suitable human antibody LC constant regions include kappa(K) or lambda. Human κ LC constant regions are preferred.

The humanized antibody may be used in the same manner as any of theother antibody targeting agents (Trojan Horses) that have previouslybeen used to deliver genes, drugs and diagnostic agents to cells byaccessing the HIR. The humanized antibody is typically linked to a drugor diagnostic compound (pharmaceutical agent) and combined with asuitable pharmaceutical carrier and administered intravenously (iv).With suitable carriers, the drug/humanized antibody complex could alsobe administered subcutaneously, intra-muscularly, intra-nasally,intra-thecally, or orally. There are a number of ways that the humanizedantibody may be linked to the pharmaceutical agent. The humanizedantibody may be fused to either avidin or streptavidin and conjugated toa pharmaceutical agent that has been mono-biotinylated in accordancewith known procedures that use the avidin-biotin linkage to conjugateantibody Trojan Horses and pharmaceutical agents together.Alternatively, the humanized antibody and pharmaceutical agent may beexpressed as a single fusion protein using known genetic engineeringprocedures.

Exemplary pharmaceutical agents to which the humanized antibody may belinked include small molecules, recombinant proteins, syntheticpeptides, antisensense agents or nanocontainers for gene delivery.Exemplary recombinant proteins include basic fibroblast growth factor(bFGF), human α-L-iduronidase (IDUA), or other neurotrophins, such asbrain derived neurotrophic factor, or other lysosomal enzymes. The useof Trojan Horses, such as the present humanized antibody, fortransporting bFGF across the BBB is described in a co-pending UnitedStates Patent Application (UC Case 2002-094-1, Attorney Docket0180-0027) that is owned by the same assignee as the present applicationand which was filed on the same day as the present application)

Once the humanized antibody is linked to a pharmaceutical agent, it isadministered to the patient in the same manner as other known conjugatesor fusion proteins. The particular dose or treatment regimen will varywidely depending upon the pharmaceutical agent being delivered and thecondition being treated. The preferred route of administration isintravenous (iv). Suitable carriers include saline or water bufferedwith acetate, phosphate, TRIS or a variety of other buffers, with orwithout low concentrations of mild detergents, such as one from theTween series of detergents. The humanized antibody/pharmaceutical agentTrojan horse compound is preferably used to deliver neuropharmaceuticalagents across the BBB. However, the humanized Trojan horse may also beused to deliver pharmaceutical agents, in general, to any organ ortissue that carries the HIR.

The following examples describe how the humanized monoclonal antibodiesin accordance with the present invention were discovered and additionaldetails regarding their fabrication and use.

EXAMPLE 1

Cloning of Murine 83-14 VH and VL Genes

Poly A+ RNA was isolated from the 83-14 hybridoma cell line (Soos et al,1986), and used to produce complementary DNA (cDNA) with reversetranscriptase. The cDNA was used with polymerase chain reaction (PCR)amplification of either the 83-14 VH or 83-14 VL gene usingoligodeoxynucleotide (ODN) primers that specifically amplify the VH andVL of murine antibody genes, and similar methods are well known (Li etal., 1999). The sequences of PCR ODNs suitable for PCR amplification ofthese gene fragments are well known (Li., 1999). The PCR products wereisolated from 1% agarose gels and the expected 0.4 Kb VH and VL geneproducts were isolated. The VH and VL gene fragments were sequentiallysubcloned into a bacterial expression plasmid so as to encode a singlechain Fv (ScFv) antibody. The ScFv expression plasmid was then used totransform E. Coli. Individual colonies were identified on agar platesand liquid cultures were produced in LB medium. This medium was used inimmunocytochemistry of Rhesus monkey brain to identify clones producingantibody that bound avidly to the Rhesus monkey brain microvasculatureor BBB. This immunocytochemistry test identified those coloniessecreting the functional 83-14 ScFv. Following identification of the83-14 VH and VL genes, the nucleotide sequence was determined in bothdirections using automatic DNA sequencing methods. The nucleotidesequence of the murine 83-14 VH (SEQ. ID. NO. 1) and the murine VL (SEQ.ID. NO. 2) gives the deduced amino acid sequence for the murine VH (SEQ.ID. NO. 3) and the murine VL (SEQ. ID. NO. 4). The amino acid sequenceis given for all 3 CDRs and all 4 FRs of both the HC and the LC of themurine 83-14 HIRMAb. The variable region of the LC is designated VL, andthe variable region of the HC is designated VH in FIG. 1.

EXAMPLE 2

Iterative Humanization of the 83-14 HIRMAb: Version 1 through Version 5

Humanization of the 83-14 MAb was performed by CDR/FR grafting whereinthe mouse FRs in the 83-14 MAb are replaced by suitable human FR regionsin the variable regions of both the LC and HC. The Kabat database wasscreened using the Match program. Either the murine 83-14 VH or the VLamino acid sequence was compared with human IgG VH or human K lightchain VL databases. Using the minimal mismatch possible, several humanIgG molecules were identified that contained FR amino sequences highlyhomologous to the amino acid sequences of the murine 83-14 VH and VL.The framework regions of the B43 human IgG1 heavy chain and the REIhuman K light chain were finally selected for CDR/FR grafting of themurine 83-14 HIRMAb.

Sets of 6 ODN primers, of 69-94 nucleotides in length, were designed toamplify the synthetic humanized 83-14 VL and VH genes (Tables 1 and 2).The ODN primers overlapped 24 nucleotides in both the 5′- and 3′-ends,and secondary structure was analyzed with standard software. Stablesecondary structure producing T_(m) of >46° C. was corrected byreplacement of first, second, or third letter codons to reduce themelting point of these structures to 32-46° C. In addition, primerscorresponding to both 5′ and 3′ ends were also designed, and theseallowed for PCR amplification of the artificial genes. These newsequences lack any consensus N-glycosylation sites at asparagineresidues.

TABLE 1 Oligodeoxynucleotides for CDR/FR grafting of VL Primer 1 FWD5′TAGGATATCCACCATGGAGACCCCCGCCCAGCTGCTGTTCCTGTTGCTGCTTTGGCTTCCAGATACTACCGGTGACATCCAGATGACCCAG-3′ (SEQ. ID. NO. 14)Primer 2 reverse 5′GTCCTGACTAGCCCGACAAGTAATGGTCACTCTGTCACCCACGCTGGCGCTCAGGCTGCTTGGGCTCTGGGTCATCTGGATGTCGCCGGT-3′ (SEQ. ID. NO. 15)Primer 3 FWD 5′ATTACTTGTCGGGCTAGTCAGGACATTGGAGGAAACTTATATTGGTACCAACAAAAGCCAGGTAAAGCTCCAAAGTTACTGATCTACGCC-3′ (SEQ. ID. NO. 16)Primer 4 reverse 5′GGTGTAGTCGGTACCGCTACCACTACCACTGAATCTGCTTGGCACACCAGAATCTAAACTAGATGTGGCGTAGATCAGTAACTTTGGAGC-3′ (SEQ. ID. NO. 17)Primer 5 FWD 5′AGTGGTAGCGGTACCGACTACACCTTCACCATCAGCAGCTTACAGCCAGAGGACATCGCCACCTACTATTGCCTACAGTATTCTAGTTCT-3′ (SEQ. ID. NO. 18)Primer 6 reverse 5′CCCGTCGACTTCAGCCTTTTGATTTCCACCTTGGTCCCTTGTCCGAACGTCCATGGAGAACTAGAATACTGTAGGCAATA-3′ (SEQ. ID. NO. 19) 5-PCR primer FWD5′TAGGATATCCACCATGGAGACCCC-3′ (SEQ. ID. NO. 20) 3-PCR primer reverse5′CCCGTCGACTTCAGCCTTTTGATT-3′ (SEQ. ID. NO. 21)

TABLE 2 Oligodeoxynucleotides for CDR/FR grafting of VH PRIMER 1 FWD5′TAGGATATCCACCATGGACTGGACCTGGAGGGTGTTATGCCTGCTTGCAGTGGCCCCCGGAGCCCACAGCCAAGTGCAGCTGCTCGAGTCTGGG-3′ (SEQ. ID. NO. 22)PRIMER 2 REVERSE 5′GTTTGTGAAGGTGTAACCAGAAGCCTTGCAGGAAATCTTCACTGAGGACCCAGGCCTCACCAGCTCAGCCCCAGACTCGAGCAGCTGCACTTG-3′ (SEQ. ID. NO. 23)PRIMER 3FWD 5′GCTTCTGGTTACACCTTCACAAACTACGATATACACTGGGTGAAGCAGAGGCCTGGACAGGGTCTTGAGTGGATTGGATGGATTTATCCTGGA-3′ (SEQ. ID. NO. 24)PRIMER 4 REVERSE 5′GCTGGAGGATTCGTCTGCAGTCAGAGTGGCTTTGCCCTTGAATTTCTCATTGTACTTAGTACTACCATCTCCAGGATAAATCCATCCAATCCA-3′ (SEQ. ID. NO. 25)PRIMER 5 FWD 5′CTGACTGCAGACGAATCCTCCAGCACAGCCTACATGCAACTAAGCAGCCTACGATCTGAGGACTCTGCGGTCTATTCTTGTGCAAGAGAGTGG-3′ (SEQ. ID. NO. 26)PRIMER 6 REVERSE 5′CATGCTAGCAGAGACGGTGACTGTGGTCCCTTGTCCCCAGTAAGCCCACTCTCTTGCACAAGAATAGAC-3′ (SEQ. ID. NO. 27) 5′-PCR PRIMER FWD5′TAGGATATCCACCATGGACTGGACCTG-3′ (SEQ. ID. NO. 28) 3′-PRC PRIMER REV5′CATGCTAGCAGAGACGGTGACTGTG-3′ (SEQ. ID. NO. 29)

The PCR was performed in a total volume of 100 μL containing 5 pmoleeach of 6 overlapping ODNs, nucleotides, and Taq and Taq extender DNApolymerases. Following PCR, the humanized VH and VL genes wereindividually ligated in a bacterial expression plasmid and E. coli wastransformed. Several clones were isolated, individually sequenced, andclones containing no PCR-introduced sequence errors were subsequentlyproduced.

The humanized VH insert was released from the bacterial expressionplasmid with restriction endonucleases and ligated into eukaryoticexpression vectors described previously (Coloma et al, 1992; U.S. Pat.No. 5,624,659). A similar procedure was performed for the humanized VLsynthetic gene. Myeloma cells were transfected with the humanized lightchain gene, and this cell line was subsequently transfected with version1 of the humanized heavy chain gene (Table 3). The transfected myelomacells were screened in a 96-well ELISA to identify clones secretingintact human IgG. After multiple attempts, no cell lines producing humanIgG could be identified. Conversely, Northern blot analysis indicatedthe transfected cell lines produced the expected humanized 83-14 mRNA,which proved the transfection of the cell line was successful. Theseresults indicated that version 1 of the humanized HIRMAb, which containsno FR amino acid substitutions, was not secreted from the cell, andsuggested the humanized HC did not properly assemble with the humanizedLC. Version 1 was derived from a synthetic HC gene containing FR aminoacids corresponding to the 25C1′Cl antibody (Bejcek et al, 1995).Therefore, a new HC artificial gene was prepared, which contained HC FRamino acids derived from a different human IgG sequence, that of the B43human IgG (Bejcek et al, 1995), and this yielded version 2 of thehumanized HIRMAb (Table 3). However, the version 2 humanized HIRMAb wasnot secreted by the transfected myeloma cell. Both versions 1 and 2contain the same HC signal peptide (Table 3), which is derived fromRechavi et al (1983). In order to evaluate the effect of the signalpeptide on IgG secretion, the signal peptide sequence was changed tothat used for production of the chimeric HIRMAb (Coloma et al, 2000),and the sequence of this signal peptide is given in Table 3. Versions 2and 3 of the humanized HIRMAb differed only with respect to the signalpeptide (Table 3). However, version 3 was not secreted from the myelomacell, indicating the signal peptide was not responsible for the lack ofsecretion of the humanized HIRMAb.

The above findings showed that simply grafting the murine 83-14 CDRs onto human FR regions produced a protein that could not be properlyassembled and secreted. Prior work had shown that the chimeric form ofthe HIRMAb was appropriately processed and secreted in transfectedmyeloma lines (Coloma et al, 2000). This suggested that certain aminoacid sequences within the FRs of the humanized HC or LC prevented theproper assembly and secretion of the humanized HIRMAb. Therefore,chimeric/humanized hybrid molecules were engineered. Version 4acontained the murine FR1 and the humanized FR2, FR3, and FR4; version 4bcontained the murine FR 3, and FR4 and the humanized FR1 and FR2 (Table3). Both versions 4a and 4b were secreted, although version 4b was moreactive than version 4a. These findings indicated amino acids withineither FR3 or FR4 were responsible for the lack of secretion of thehumanized HIRMAb. The human and murine FR4 differed by only 1 amino acid(Table 3); therefore, the sequence of FR4 was altered by site-directedmutagenesis to correspond to the human sequence, and this version wasdesignated version 5 (Table 3). The version 5 HIRMAb corresponded to theoriginal CDR-grated antibody sequence with substitution of the humansequence in FR3 of the VH with the original murine sequence for the FR3in the VH. The same CDR-grafted LC, without any FR substitutions, wasused in production of all versions of the humanized HIRMAb. Thiscorresponds with other work showing no FR changes in the LC may berequired (Graziano et al, 1995).

TABLE 3 Iterations of Genetic Engineering ofHumanized HIRMAb Heavy Chain             FR1      CDR1         FR2Version 5 QVQLLESGAELVRPGSSVKISCKAS GYTFTNYDIH WVKQRPGQGLEWIG Version 4bQVQLLESGAELVRPGSSVKISCKAS GYTFTNYDIH WVKQRPGQGLEWIG Version 4aQVQLQESGPELVKPGALVKISCKAS GYTFTNYDIH WVKQRPGQGLEWIG Version 3QVQLLESGAELVRPGSSVKISCKAS GYTFTNYDIH WVKQRPGQGLEWIG Version 2QVQLLESGAELVRPGSSVKISCKAS GYTFTNYDIH WVKQRPGQGLEWIG Version 1QVQLLESGAELVRPGSSVKISCKAS GYTFTNYDIH WVKQRPGQGLEWTG murineQVQLQESGPELVKPGALVKISCKAS GYTFTNYDIH WVKQRPGQGLEWIG human B43QVQLLESGAELVRPGSSVKISCKAS GYAFSSYWMN WVKQRPGQGLEWIG 1 26 36         CDR2                FR3 Version 5 WIYPGDGSTKYNEKFKGKATLTADKSSSTAYMHLSSLTSEKSAVYFCAR Version 4b WIYPGDGSTKYNEKFKGKATLTADKSSSTAYMHLSSLTSEKSAVYFCAR Version 4a WIYPGDGSTKYNEKFKGKATLTADESSSTAYMQLSSLRSEDSAVYSCAR Version 3 WIYPGDGSTKYNEKFKGKATLTADESSSTAYMQLSSLRSEDSAVYSCAR Version 2 WIYPGDGSTKYNEKFKGKATLTADESSSTAYMQLSSLRSEDSAVYSCAR Version 1 WIYPGDGSTKYNEKFKGQATLTADKSSSTAYMQLSSLTSEDSAVYSCAR murine WIYPGDGSTKYNEKFKGKATLTADKSSSTAYMHLSSLTSEKSAVYFCAR human B43 QIWPGDGDTNYNGKFKGKATLTADESSSTAYMQLSSLRSEDSAVYSCAR 50 67        CDR3     FR4 Version 5-----------EWAY WGQGTTVTVSA (SEQ. ID. NO. 5) Version 4b -----------EWAYWGQGTLVTVSA (SEQ. ID. NO. 11) Version 4a -----------EWAYWGQGTTVTVSA (SEQ. ID. NO. 10) Version 3 -----------EWAYWGQGTTVTVSA (SEQ. ID. NO. 9 Version 2 -----------EWAYWGQGTTVTVSA (SEQ. ID. NO. 8) Version 1 -----------EWAYWGQGTTVTVSA (SEQ. ID. NO. 7) murine -----------EWAYWGQGTLVTVSA (SEQ. ID. NO. 3) human B43 RETTTVGRYYYAMDYWGQGTTVT--- (SEQ. ID. NO. 12) 99         99 103      113

Version 1 was designed using the FRs of the human 25ClCl IgG heavy chain(HC) variable region (VH). Version 1 did not produce secreted hIgG fromthe transfected myeloma cells despite high abundance of the HC mRNAdetermined by Northern blot analysis.

Version 2 was re-designed using the FRs of the human B43 IgG HC variableregion. The peptide signal #1 (MDWTWRVLCLLAVAPGAHS) (SEQ. ID. NO. 49) inversions 1 and 2 was replaced by signal peptide #2 (MGWSWVMLFLLSVTAGKGL)(SEQ. ID. NO. 50) in version 3. The FRs and CDRs in version 2 and 3 areidentical. The signal peptide #2 was used for versions 4a, 4b and 5.

Version 4a has human FRs 2, 3 and 4 and murine FR1.

Version 4b has human FRs 1 and 2, and murine FRs 3 and 4

Version 5 was produced using the human FRs 1, 2 and 4 and the murineFR3.

Versions 4a, 4b and 5 produced secreted hIgG, whereas version 1, 2, and3 did not secrete IgG. Among versions 4a, 4b, and 5, version 5 containsfewer murine framework amino acid substitutions and is preferred.

The version 5 form of the protein was secreted intact from thetransfected myeloma lines. The secreted version 5 humanized HIRMAb waspurified by protein A affinity chromatography and the affinity of thisantibody for the HIR was tested with an immunoradiometric assay (IRMA),which used [¹²⁵I]-labeled murine 83-14 MAb as the ligand as describedpreviously (Coloma et al, 2000). These results showed that the affinityof the antibody for the HIR was retained. In the IRMA, the antigen wasthe extracellular domain of the HR, which was produced from transfectedCHO cells and purified by lectin affinity chromatography of CHO cellconditioned medium. The dissociation constant (K_(D)) of the murine andVersion 5 humanized 83-14 HIRMAb was 2.7±0.4 nM and 3.7±0.4 nM,respectively. These results show that the 83-14 HIRMAb has beensuccessfully humanized using methods that (a) obtain the FR regions ofthe HC and of the LC from different human immunoglobulin molecules, and(b) do not require the use of molecular modeling of the antibodystructure, as taught in U.S. Pat. No. 5,585,089. Similar to otherapplications (Graziano et al., 1995), no FR amino acid changes in the LCof the antibody were required.

EXAMPLE 3

Binding of the Humanized HIRMAb to the Human BBB

Prior work has reported that the radiolabelled murine HIRMAb avidlybinds to human brain capillaries with percent binding approximately 400%per mg protein at 60-120 minutes of incubation (Pardridge et al., 1995).Similar findings were recorded with radiolabelled Version 5 humanizedHIRMAb in this example. When human brain capillaries were incubated in aradioreceptor assay with [¹²⁵I] Version 5 humanized HIRMAb, the percentbinding approximated 400% per mg protein by 60 minutes of incubation atroom temperature, and approximated the binding to the human braincapillary of the [¹²⁵I-chimeric HIRMAb (see FIGS. 2A and 2B). Incontrast, the binding of a nonspecific IgG to human brain capillaries isless than 5% per mg protein during a comparable incubation periodPardridge et al., 1995). This example shows that the Version 5 humanizedHIRMAb was avidly bound and endocytosed by the human brain capillary,which forms the BBB in vivo.

EXAMPLE 4

Transport of Humanized HIRMAb Across the Primate BBB In Vivo

The humanized Version 5 HIRMAb was radiolabelled with 125-Iodine andinjected intravenously into the adult Rhesus monkey. The animal wassacrificed 2 hours later and the brain was removed and frozen. Cryostatsections (20 micron) were cut and applied to X-ray film. Scanning of thefilm yielded an image of the primate brain uptake of the humanizedHIRMAb (FIG. 3). The white matter and gray matter tracts of the primatebrain are clearly delineated, with a greater uptake in the gray matteras compared with the white matter. The higher uptake of the human HIRMAbin the gray matter, as compared with the white matter, is consistentwith the 3-fold higher vascular density in gray matter, and 3-foldhigher nonspecific IgG is injected into Rhesus monkeys there is no brainuptake of the antibody (Pardridge et al., 1995). These filmautoradiography studies show that the humanized HIRMAb is able to carrya drug (iodine) across the primate BBB in vivo. Based on the highbinding of the humanized HIRMAb to the human BBB (FIG. 2), similarfindings of high brain uptake in vivo would be recorded in humans.

EXAMPLE 5

Affinity Maturation of the Antibody by CDR or FR Amino Acid Substitution

The amino acid sequences of the VH of the HC and of the VL of the LC aregiven in FIG. 4 for the Version 5 humanized HIRMAb, the murine 83-14HIRMAb, and either the B43 HC or the REI LC antibodies. Given the CDRamino sequences in FIG. 4, those skilled in the art of antibodyengineering (Schier et al., 1996) may make certain amino acidsubstitutions in the 83-14 HC or LC CDR sequences in a process called“affinity maturation” or molecular evolution. This may be performedeither randomly or guided by x-ray diffraction models of immunoglobulinstructure, similar to single amino acid changes made in the FR regionsof either the HC or the LC of an antibody (U.S. Pat. No. 5,585,089).Similarly, given the FR amino acid sequences in FIG. 4, those skilled inthe art can make certain amino acid substitutions in the HC or LC FRregions to further optimize the affinity of the HIRMAb for the targetHIR antigen. The substitutions should be made keeping in mind thesequence identity limitations set forth previously for both the FR andCDR regions. These changes may lead to either increased binding orincreased endocytosis or both.

EXAMPLE 6

Humanized HIRMAb/α-L-iduronidase Fusion Protein

α-L-iduronidase (IDUA) is the enzyme missing in patients with Hurlersyndrome or type I mucopolysaccharidosis (MPS), which adversely affectsthe brain. The brain pathology ultimately results in early death forchildren carrying this genetic disease. IDUA enzyme replacement therapy(ERT) for patients with MPS type I is not effective for the braindisease, because the enzyme does not cross the BBB. This is a seriousproblem and means the children with this disease will die early eventhough they are on ERT. The enzyme could be delivered across the humanBBB following peripheral administration providing the enzyme is attachedto a molecular Trojan horse such as the humanized HIRMAb. The IDUA maybe attached to the humanized HIRMAb with avidin-biotin technology. Inthis approach, the IDUA enzyme is mono-biotinylated in parallel with theproduction of a fusion protein of the humanized HIRMAb and avidin. Inaddition, the IDUA could be attached to the humanized HIRMAb not withavidin-biotin technology, but with genetic engineering that avoids theneed for biotinylation or the use of foreign proteins such as avidin. Inthis approach, the gene encoding for IDUA is fused to the region of thehumanized HIRMAb heavy chain or light chain gene corresponding to theamino or carboxyl terminus of the HIRMAb heavy or light chain protein.Following construction of the fusion gene and insertion into anappropriate prokaryotic or eukaryotic expression vector, the HIRMAb/IDUAfusion protein is mass produced for purification and manufacturing. Theamino acid sequence and general structure of a typical MAb/IDUA fusionprotein is shown in FIG. 5 (SEQ. ID. NO. 48). In this construct, theenzyme is fused to the carboxy terminus of the heavy chain (HC) of thehumanized HIRMAb. The amino acid sequence for the IDUA shown in FIG. 5is that of the mature, processed enzyme. Alternatively, the enzyme couldbe fused to the amino terminus of the HIRMAb HC or the amino or carboxyltermini of the humanized HIRMAb light chain (LC). In addition, one ormore amino acids within the IDUA sequence could be modified withretention of the biological activity of the enzyme. Fusion proteins oflysosomal enzymes and antibodies have been prepared and these fusionproteins retain biological activity (Haisma et al, 1998). The fusiongene encoding the fusion protein can be inserted in one of severalcommercially available permanent expression vectors, such as pCEP4, andcell lines can be permanently transfected and selected with hygromycinor other selection agents. The conditioned medium may be concentratedfor purification of the recombinant humanized HIRMAb/IDUA fusionprotein.

EXAMPLE 7

Role of Light Chain (LC) in Binding of HIRMAb to the Human InsulinReceptor

Myeloma cells (NSO) were transfected with a plasmid encoding the eitherthe humanized HIRMAb light chain or “surrogate light chain”, which wasan anti-dansyl MAb light chain (Shin and Morrison, 1990). Theanti-dansyl light chain is derived from the anti-dansyl IgG, wheredansyl is a common hapten used in antibody generation. Both the myelomaline transfected with the humanized HIRMAb light chain, and the myelomaline transfected with the surrogate light chain were subsequentlytransfected with a plasmid encoding the heavy chain of the chimericHIRMAb. One cell line secreted an IgG comprised of the anti-HIRMAbchimeric heavy chain and the anti-HIRMAb humanized light chain, and thisIgG is designated chimeric HIRMAb heavy chain/humanized HIRMAb lightchain IgG. The other cell line secreted an IgG comprised of a chimericHIRMAb heavy chain and the anti-dansyl light chain, and this IgG isdesignated chimeric HIRMAb HC/dansyl LC IgG. Both cells lines secretedIgG processed with either the humanized HIRMAb light chain or theanti-dansyl light chain, as determined with a human IgG ELISA on themyeloma supernatants. These data indicated the chimeric HIRMAb heavychain could be processed and secreted by myeloma cells producing anon-specific or surrogate light chain. The reactivity of these chimericantibodies with the soluble extracellular domain (ECD) of the HIR wasdetermined by ELISA. The HIR ECD was purified by lectin affinitychromatography of the conditioned medium of CHO cells transfected withthe HIR ECD as described previously (Coloma et al, 2000). In the HIR ECDELISA, the murine 83-14 HIRMAb was used as a positive control and mouseIgG2a was used as a negative control. The negative control producednegligible ELISA signals; the standard curve with the murine 83-14 MAbgave a linear increase in absorbance that reached saturation at 1 μg/mlmurine 83-14 MAb. The immune reaction in the ELISA was quantified with aspectrophotometer and maximum absorbance at 405 nm (A405) in this assaywas 0.9. All isolated myeloma clones secreting the chimeric HIRMAb heavychain/humanized HIRMAb light chain IgG were positive in the HIR ECDELISA with immuno-reactive levels that maximized the standard curve. Inaddition, the myeloma clones secreting the chimeric HIRMAb HC/dansyl LCIgG also produced positive signals in the HIR ECD ELISA, and the A405levels were approximately 50% of the A405 levels obtained with thechimeric HIRMAb heavy chain/humanized HIRMAb light chain IgG. Thesefindings indicate the light chain plays a minor role in binding of theHIRMAb to its target antigen, which is the extracellular domain of thehuman insulin receptor. This interpretation is supported by the findingthat no FR substitutions in the humanized LC were required to enableactive binding of the humanized HIRMAb to the HIR ECD (see Example 2).These findings show that large variations in the amino acid sequence ofthe HIRMAb light chain (50% and more) can be made with minimal loss ofbinding of the intact humanized HIRMAb to the target HIR antigen.Accordingly, a wide variety of LC's may be used to prepare humanizedantibodies in accordance with the present invention provided that theyare compatible with the HC. The LC is considered to be “compatible” withthe HC if the LC can be combined with the HC and not destroy the abilityof the resulting antibody to bind to the HIR. In addition, the LC mustbe human or sufficiently humanized so that any immunogenic reaction inhumans is minimized. Routine experimentation can be used to determinewhether a selected human or humanized LC sequence is compatible with theHC.

Having thus described exemplary embodiments of the present invention, itshould be noted by those skilled in the art that the within disclosuresare exemplary only and that various other alternatives, adaptations andmodifications may be made within the scope of the present invention.Accordingly, the present invention is not limited to the above preferredembodiments and examples, but is only limited by the following claims.

BIBLIOGRAPHY

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What is claimed is:
 1. A method for increasing the ability of aneuropharmaceutical agent to cross the human blood brain barrier, themethod comprising genetically fusing said neuropharmaceutical agent to ahumanized antibody wherein the humanized antibody has antigenspecificity for the human insulin receptor; and, wherein the humanizedantibody comprises a V_(H) domain comprising the amino acid sequence ofSEQ ID NO: 5, comprises a V_(L) domain comprising the amino acidsequence of SEQ ID NO: 6, or comprises a V_(H) domain comprising theamino acid sequence of SEQ ID NO:5 and a V_(L) domain comprising theamino acid sequence of SEQ ID NO:6.
 2. A method according to claim 1,wherein said neuropharmaceutical agent is an enzyme.
 3. A method fortargeting a pharmaceutical agent to the human insulin receptor in vivo,the method comprising genetically fusing said pharmaceutical agent to ahumanized antibody wherein the humanized antibody has antigenspecificity for the human insulin receptor; and, wherein the humanizedantibody comprises a V_(H) domain comprising the amino acid sequence ofSEQ ID NO: 5, comprises a V_(L) domain comprising the amino acidsequence of SEQ ID NO: 6, or comprises a V_(H) domain comprising theamino acid sequence of SEQ ID NO:5 and a V_(L) domain comprising theamino acid sequence of SEQ ID NO:6.
 4. A method according to claim 3,wherein said neuropharmaceutical agent is an enzyme.
 5. The method ofclaim 1, wherein said neuropharmaceutical agent is a human α-iduronidaseenzyme (IDUA).
 6. The method of claim 3, wherein saidneuropharmaceutical agent is a human α-iduronidase enzyme (IDUA).
 7. Themethod of claim 5, wherein the IDUA is fused to the humanized antibodyat a carboxyl terminus of a heavy chain of the humanized antibody. 8.The method of claim 6, wherein the IDUA is fused to the humanizedantibody at a carboxyl terminus of a heavy chain of the humanizedantibody.